Improvements in Manholes and Manhole Covers Applicable to Drains and for other Purposes.

摘要

4790. Preston, E. J., and Jakeman, G. E. March 13. Grant of Patent refused. Manhole doors and frames for drains and other purposes. The cover h is sealed by a flange i, which rests upon asbestos packing g, and also by a flange m, which dips into a trough o supplied with water by the condensation on the domed under surface of the cover.